The present invention relates generally to an apparatus for measuring the characteristics of semiconductor devices and, more particularly, to a high-voltage power supply capable of outputting a high voltage adequate to measure high breakdown voltages.
The breakdown voltage of a semiconductor diode or other device has been heretofore measured as follows. A reverse voltage is applied to the device, and the value of the voltage is varied. The reverse voltage measured when the electric current induced by the breakdown reaches a predetermined value is defined as its breakdown voltage. During this measurement, if the voltage is applied for a long time, heat generated inside the device may destroy the device itself. Therefore, the applied voltage is required to take the form of pulses, for example high-speed pulses having a pulse duration of about 1 ms. If such pulses have a pulse height of tens of volts, then they can be easily produced. However, when a device whose breakdown voltage is as high as 1 KV, for example, undergoes measurement, it is not easy to produce high-speed pulses necessary for the measurement.
One conceivable method of producing pulses of such a high voltage is to control a switching regulator by analog feedback. Another conceivable method consists in stepping up an AC voltage by a transformer and controlling the AC voltage by a sliding transformer. However, none of these methods offer satisfactory voltage response speeds or frequency response characteristics. In a system where a linear amplifier comprising transistors resistant to high voltages is controlled by analog feedback, a large amount of idling current is necessary to provide rapid response. Consequently, a large amount of electric power is consumed.